Most hens like darkness and privacy when laying. It makes them feel like they are "hiding" their eggs. We must work with the hen's instinct.

Thus, most use simple 16" square boxes. Some even hang a bit of burlap over the front, increasing the privacy and darkness. Placing a few golf balls in the nesting box often is a visual cue that works, at first. Also, make sure your roots are higher than the laying box. The laying boxes should be reasonably low until the hens all lay in them. I never raise mine up very far.